The present invention relates to an electrode holder; that is, more particularly, to a self-adjustable electrode holder for automatically positioning electroencephalographic electrodes.
An electroencephalograph is an instrument for recording the electrical activity of an animal brain which is sensed by means of electrodes positioned at the surface of the scalp. The instrument is used in the study of the normal brain as well as in the diagnosis of epilepsy, trauma, tumors and other degenerations of the brain.
An electroencephalograph conventionally comprises a plurality of electrodes, a holding means for maintaining the electrodes in contact with the scalp, an electronic circuit including amplifiers and controls for processing electrical signals received at the electrodes, and an output device, such as an oscillograph, for converting the data into readable form. The electrodes, the electronic circuit and the output device are, of course, interconnected by means of wires or cables.
Neither the electronic circuit nor the output device form a part of the present invention so that no description of their construction or method of operation need be given in this specification.
An electroencephalographic technician normally administers or obtains an electroencephalograph from a patient in the following manner: While the patient is seated, the technician carefully measures the patient's head and determines the points at which the electrodes are to be placed. Electrodes are then secured to the patient's head at these points by means of a conductive paste, in the nature of an adhesive, which hardens (but which can be subsequently washed away with soap and water). Thereafter, the technician operates the controls of the electronic circuit and determines whether each of the electrodes is in proper electrical contact with the scalp. If so, the signals received at the electrodes are recorded for subsequent reading by a neurologist.
The electroencephalographic technique described above requires both knowledge and skill to properly locate and attach the electrodes to the patient's head. Moreover, this process is time-consuming. It normally takes an excess of 45 minutes to completely "wire" a patient in preparation for an electroencephalographic recording.
Various attempts have been made to provide a "helmet" or other holder device which would enable a technician, without extensive training, to properly position and hold the electroencephalographic electrodes in contact with a patient's head within a short period of time, say five to 10 minutes. These prior art attempts have been mildly successful but have not achieved wide use in the field because the electrode positions for each different head still have to be measured and the holder or helmet adjusted to apply the electrodes at these positions. In addition, it is necessary, in some cases, to adjust the helmet itself to the specific size of a patient's head. Furthermore, depending upon the type of electrode used, it has been difficult to make proper contact between the electrode and the scalp.
It should be noted that the positions of electrodes on the head of a patient have been standardized since about 1959 so that electroencephalographs obtained from various patients may be compared. This standard, which is called the International 10/20 System, is well known and is described by H. H. Jasper in EEG Clinical Neurophysiology, Vol. 10, page 371 (1958).